Merge pull request #924 from nag5000/fix/setting-empty-value-clears-files

Author: rwjblue

addon-test-support/@ember/test-helpers/dom/fire-event.ts

@@ -267,6 +267,25 @@ function buildFileEvent(
       value: files,
       configurable: true,
     });
+
+    let elementProto = Object.getPrototypeOf(element);
+    let valueProp = Object.getOwnPropertyDescriptor(elementProto, 'value');
+    Object.defineProperty(element, 'value', {
+      configurable: true,
+      get() {
+        return valueProp!.get!.call(element);
+      },
+      set(value) {
+        valueProp!.set!.call(element, value);
+
+        // We are sure that the value is empty here.
+        // For a non-empty value the original setter must raise an exception.
+        Object.defineProperty(element, 'files', {
+          configurable: true,
+          value: [],
+        });
+      },
+    });
   }
 
   Object.defineProperty(event, 'target', {

tests/unit/dom/select-files-test.js

@@ -80,4 +80,20 @@ module('DOM Helper: selectFiles', function (hooks) {
 
     assert.verifySteps(['change', 'empty']);
   });
+
+  test('setting an empty value resets selected files', async function (assert) {
+    element = buildInstrumentedElement('input');
+    element.setAttribute('type', 'file');
+
+    element.addEventListener('change', e => {
+      assert.step(e.target.files[0].name);
+    });
+
+    await setupContext(context);
+    await triggerEvent(element, 'change', { files: [imageFile] });
+    element.value = '';
+
+    assert.verifySteps(['change', 'image-file.png']);
+    assert.equal(element.files.length, 0, 'Files should be empty');
+  });
 });